In containerd, reviewers can, well, review pull requests. That’s pretty much self-explanatory. Here is the official definition from containerd’s Project Governance document.
A reviewer is a core role within the project. They share in reviewing issues and pull requests and their LGTM counts towards the required LGTM count to merge a code change into the project.
Reviewers are part of the organization but do not have write access. Becoming a reviewer is a core aspect in the journey to becoming a maintainer.
Technically speaking, anyone can review pull requests and I’ve been reviewing them. But now my approval actually counts towards the required LGTM count.